Figure 1. Above is a SuperPro Designer simulation of DSM's current algal fermentation process, which was used to simulate the biomass stream going into DSM's solventless oil extraction.

Figure 2. Above is a SuperPro Designer simulation of DSM's solventless oil extraction process, which was used to simulate the waste stream (including its components) that our design solution utilizes (the "Wastewater" and "Solid Biomass Waste" streams).

Figure 3. The SuperPro Designer simulation above is a condensed version of our final solution. DSM's waste stream is divided into wastewater and biomass waste. The biomass waste undergoes recycling to replace yeast extract in DSM's fermentation process. The wastewater is used to separate out the high-value compound, beta-glucan.

Figure 4. Above is the biomass recycling process simulation, which uses a simplified version of DSM's fermentation and solventless extraction. This process only includes one additional unit operation, which is an evaporator. The evaporator is used to evaporate and dry algae biomass, which is then recycled back into DSM's process to replace yeast extract. Using the assumption that 9% of the waste stream is biomass, it was calculated that 22,500 kg of biomass waste per batch could be used to replace yeast extract going into the fermenter. This quantity is 27.9% of the yeast extract used in each batch.

Figure 5. Above is the final beta-glucan extraction process simulation. The wastewater contains soluble beta-glucan which was released from algal cell walls during DSM's process (Devile et al., 2004). The wastewater is sent through ultrafiltration, diafiltration, and evaporation to remove water and any compounds smaller and larger than beta-glucan. The stream is then sent to a reactor where ethanol is added to precipitate out beta-glucan. This stream is then sent to a centrifuge, which separates the water with ethanol and beta-glucan, our final product. The water and ethanol undergo distillation to recycle ethanol back into the process to reduce carbon emissions and abide by the standards mentioned on the "Constraints, Criteria, and Standards" page.

This SuperPro Designer simulation was able to separate out 2,113.56 kg of beta-glucan per batch assuming that about 1% (w/w) of the approximately 264,000 L wastewater stream was beta-glucan with a 75% recovery. It was assumed that 1% (w/w) of the waste stream was beta-glucan as a conservative assumption to ensure this process was profitable, and a 75% recovery was assumed, as studies that performed ethanol precipitation of beta-glucan were able to achieve this recovery (Devile et al, 2004). The amount of precipitated beta-glucan will obviously fluctuate depending on what percentage of the waste stream consists of beta-glucan on a given run.

To learn more about our processes, make sure to check our Final Report under the "Resources" tab!

Above are the breakdowns of the capital investment and annual profits for the beta-glucan extraction process. The capital investment considered costs associated with equipment, installation, and process piping. The total capital cost for beta-glucan extraction would be $24.5 million. The annual profits for beta-glucan extraction would be $2.8 million considering the expenses associated with materials, utility, and labor. The beta-glucan revenue was calculated using the results from our simulation and assumed beta-glucan could be sold at $4/kg and there are 400 batches/year. The payback period is 8.79 years.

Above are the breakdowns of the capital investment and annual profits for the biomass recycling process. The capital investment considered costs associated with equipment, installation, and process piping. The total capital cost for biomass recycling would be $9 million. The annual profits for biomass recycling would be $2.9 million considering the expenses associated with utility and labor. The revenue was calculated using the results from our simulation and assumed there are 400 batches/year and biomass recycling would increase DHA production, as shown by studies conducted by Yin et al. (2018). The payback period is 3.13 years.

Check our Final Report under the "Resources" tab to learn more about our economic analysis.

It is recommended that these solutions be implemented together. The annual profits when implementing both solutions would be $5.7 million with a payback period of 5.9 years, and the waste volume would decrease by 22,500 kg/batch. Further testing must be conducted before industrial scale implementation.

Devile, C., Damas, J., Forget, P., Dandrifosse, G., & Peulen, O. (2004). Laminarin in the dietary fibre concept. J. Sci. Food Agric., 84(9), 1030-1038. https://doi.org/10.1002/jsfa.1754

Yin, F. W., Guo, D. S., Ren, L. J., Ji, X. J., & Huang, H. (2018). Development of a method for the valorization of fermentation wastewater and algal-residue extract in docosahexaenoic acid production by Schizochytrium sp. Bioresour. Technol., 266(2018), 482-487. https://doi.org/10.1016/j.biortech.2018.06.109